1. Field of the Invention
The present invention relates generally to semiconductor manufacturing and, more particularly, to a method and apparatus for providing a confinement ring drive that provides proportional spacing between the confinement rings over a travel range.
2. Description of the Related Art
During the manufacturing of semiconductor-based devices, it is common to deposit layers of material onto a substrate. Each of the layers of material may undergo an etching process. Etching of the layers may be accomplished by a wide variety of techniques including plasma-enhanced etching.
The plasma etchers performing these operations may include confinement rings to confine the plasma within a region of the etch chamber. The confinement rings serve to confine the plasma and also protect the chamber walls. There are dynamic limits to how wide the confinement ring spacing can be driven to control pressure if equal gaps between all of the confinement rings are not established. The capability of proportional confinement ring spacing can effectively increase the dynamic range of pressure control while minimizing undesired effects such as plasma unconfinement when these non-proportional spacing limits are exceeded.
In view of the foregoing, there is a need for a method and apparatus that provides for uniform movement of the confinement rings over a range of travel of the confinement rings.